1. Field of the Invention
The invention relates generally to the field of photography and particularly to a system for holding a filmstrip against a platen of a photographic printer.
2. Descriotion of the Prior Art
Photographic printers use film negatives to make prints. Most photographic printers contain a linear array scanning station. As each frame of the filmstrip (negatives) pass over the aperture of the linear array scanning station, devices contained within the photographic printer scan each filmstrip frame. The devices obtain information about the density, color balance and composition of each frame of the filmstrip so that the photographic printer may use this information to adjust various photographic printer parameters to produce better quality prints.
In order to obtain the above information, the filmstrip has to be placed flat over the aperture of the linear array scanning station. The prior art utilized tension gates or deflectors to hold the film flat against the aperture of the scanning station and drive rollers to move the filmstrip over the aperture of the scanning station. The deflectors pushed the filmstrip against the aperture plate of the scanning station and the drive rollers moved the filmstrip past the aperture and pushed the filmstrip against the deflectors. The interaction of the filmstrip with the deflectors and aperture plate caused tension in the filmstrip or web. If the tension in the filmstrip exceeded the frictional drive capabilities of the drive rollers, the filmstrip would slip relative to the drive rollers rotation. When the above happened, the photographic printer would not meter the filmstrip correctly and the correct frame would not appear at the aperture of the scanner. Sometimes, the drive rollers exerted a large amount of force on the filmstrip, which caused the filmstrip to break. The foregoing caused at least one negative to be damaged, the loss of some photographic paper and the printer to stop processing film until the filmstrip could be respliced. Thus, one of the disadvantages of the above prior art system was that tensions in the filmstrip caused the system to malfunction.
Another disadvantage of the above prior art system was that sometimes the deflectors scratched the picture portion of the filmstrip and damaged the quality of the resulting prints.
Another prior art system utilized a clamping arrangement to keep the filmstrip flat against a plate of a scanner that had an aperture and drive rollers to move the filmstrip past the aperture of the plate. The clamping system was essentially a four-sided picture frame with a hole in the middle. The drive rollers would move the filmstrip between the aperture of the plate and the four-sided picture frame. As each frame of the filmstrip passed over the aperture of the plate, the four-sided frame was actuated and pushed the filmstrip against the aperture of the plate. Thus, for every frame that moved past the aperture of the plate, the four-sided frame moved down and up.
One of the disadvantages of the above system was that the system was slow, since time was required to move the frame down and up.
Another disadvantage of the above system was that the system had additional moving parts, which had a tendency to become inoperative.
In order to make photographic printers more efficient during reorder operation, the various frames of the filmstrip that a customer wanted reprinted were attached to a paper carrier. The paper carrier formed a roll containing many frames that were able to be rapidly moved through the printer. Whereas, if the filmstrip was not connected to a paper carrier individual frames on a four-frame filmstrip would have to be moved separately through the printer. The above deflectors and clamping system caused additional tension in the filmstrip and paper carrier which caused the filmstrip and paper carrier combination to delaminate. Oftentimes the printer was not able to print frames of the filmstrip that were not connected to the paper carrier. Sometimes the increased tension caused the paper carrier and/or filmstrip to break, which caused the printer to be shut down until the paper carrier was reattached to the filmstrip. Thus, the above deflectors and clamping systems had additional problems when the photographic printers were printing reordered filmstrips.